Extruded acrylic has a more consistent thickness than cast acrylic, however it has a limited range of colours and thicknesses. It is a tradename of Lucite International and is polymethyl methacrylate (PMMA) acrylic sheet which is manufactured from methyl methacrylate monomer (MMA). Cast acrylic plexiglass sheet gives the high molecular weight benefits of cast acrylic , combined with outstanding thickness consistency! It polishes to a crystal clear clarity and is the superior brand for all types of projects. LIGHT IN WEIGHT Acrylic (specific gravity 9) is less than half the weight when compared to inorganic glass.